262 W. Lilljeborg on the Genera Peltogaster and Liriope. 



spot, no doubt indicating the mouth. Towards the base this 

 part of the body becomes much narrower, forming a neck. No 

 external buccal organs are visible. 



The posterior part of the body forms merely a matrix or ovisac. 

 It is a reniform sac, convex above and below, with no impressions, 

 folds, or sutures above, but furnished beneath with a longitudinal 

 fissure (fig. 3) or aperture, through which the young escape. 

 This part is of a reddish or flesh-colour, from the red ova and 

 young shining through the transparent skin. At the point 

 where the anus appears to be, there are some brown spots. 

 During the contraction of the animal, some transverse folds ap- 

 peared on the upper surface (fig. 1 a) ; these persisted when the 

 animal was preserved in spirit, and perhaps indicate segments. 

 At the posterior extremity of the fissure of the matrix is a round 

 aperture ; no doubt, the anus. The skin of the matrix, although 

 transparent, is firm and rather thick. 



Upon the cephalothorax, whilst the animal was still attached 

 to the Peltogaster ; there was a delicate and transparent pendant 

 membrane, probably a cast skin. On the upper surface behind 

 the neck there are an opake and thick skin and two areas of 

 fibrous structure. The evolution of the valves, or the integument 

 of the matrix, probably commences from these areas. The retro- 

 grade metamorphosis in this animal is greater than in Bopyrus ; 

 there are no antennae, buccal laminae, feet, or branchial laminae. 



The Male. Prof. Lilljeborg did not detect the male upon or 

 in the Peltogaster to which the female was attached, or upon the 

 female herself. He thinks it very probable that the Liriope 

 pygmcea described and figured by Rathke was a young male. On 

 comparing it with the description and figures of Kroyer, repre- 

 senting a younger male of his Bopyrus abdominalis*, which is 

 the same as Phryxus Hippolytes of Rathke, the resemblance is 

 striking. Kroyer' s young male Bopyrus was ^ line, and Rathke's 

 Liriope scarcely 1 line in length. Thus, judging from their 

 size, the latter was more developed than the former. The form 

 of the body, the antennae, the legs, and caudal appendages, are 

 very similar. There are some differences in the form of the 

 posterior pair of thoracic feet ; but their structure is very charac- 

 teristic, and conformable to that occurring in Liriope ; and this 

 furnished the author with one of his best reasons for identifying 

 the young of the animal found by him upon Peltogaster Paguri 

 with Rathke's Liriope. In Liriope Rathke found six pairs of 

 abdominal feet, Kroyer only five in the young male of Bopyrus ; 

 but Rathke has only four in his figure of Liriope, and the author 

 found only five in the young of his species. According to 



* Naturhistorisk Tidskrift, Bd. 3. p. 291, tab. 1. figs. 21-24, tab. 2. 

 figs. 1-3; Voyage en Scandinavie, pi. 29. fig. 1 t-u. 



